This research project is to study what can be achieved for cancer patients treated with megavoltage therapy alone or in combined programs with surgery or chemotherapy. Evaluating the results of treatment and coding cases in such areas as head and neck, cervix, uterus, bladder, breast, bronchogenic and special coded cases such as radical neck dissections, complications in cancer of the cervix and other areas, will enable modification of treatment to improve end results. As stated in the past, the hypothetical superiority of megavoltage radiation must be evaluated separately for the various purposes of radiation therapy. Although there is no statistical proof of the superiority of megavoltage roentgenotherapy, the universal impression is that it is a more effective therapeutic tool for control of several groups of cancers; such as, tumors of the oropharynx and the urinary bladder. Through December 1973 there have been approximately 24,000 patients treated with several modalities of megavoltage equipment, or in combined programs such as the Cobalt-60, 22 Mev Betatron, 18 Mev Betatron (using electron beam or photon beam) and a 25 Mev Linear Accelerator. Of these, more than 19,600 cases have been coded into a detailed study code or schedule designed for each specific site of cancer. Survival rates and standard errors by totals, stage of disease, histology and other pertinent factors are figured by the modified life table method (Berkson, Gage and Greenwood). In addition, there are detailed studies of sites and causes of failure and of staging of primary and regional nodes. All treated cases in Radiotherapy are analyzed.